Do we really need a constitution? England and New Zealand don't have constitutions and yet they function. If we think we do need a constitution, do we want to keep what we have, or should we call for a constitutional convention? Some recent and forthcoming books tackle these subjects. If you are interested, you might want to check them out:

Saluting the World Bank, which one year ago announced it would provide its research outputs and knowledge products open access, making its research as widely available as possible. Search 2,000+ World Development Indicators (WDI) from World Bank data sets covering 200+ countries today!